Transmitting device



Oct. 16 1923 J. B. SPEED wamsmwmue DEVICE Filed Nov. 19, 9

Patented Oct. 16, 1923.

UNITED STATES PATENT FFlE.

JAMES BUCKNER SPEED, OF NEW YORK. N. Y., ASSIGNOR T0 WESTERN ELECTRIC COM- PANY, INCORIE'ORATED, OF NEW YORK. N. Y., A CORPORATION OF NEW YORK.

TRANSMITTING DEVICE.

Application filed November 19. 1919. Serial No. 339.217.

To all whom it may concern."

Be it known that l, JAMES BUCKNER Srrzrn. a citizen of the United States of America residin at New York, in the county of New York, State of New York.

' are inv ented certain new and useful Im- ;rovements in Transmitting Devices, of which the following is a full, clear, concise, and exact description This invention relates in general to trans initting devices and particularly to transmitters for signaling purposes An object of the invention is to provide a sound responsive device. which shall be solectively responsive to vibrations of one or more particular frequencies and which shall be unresponsive to vibrations of other frequencies.

The invention comprises a pair of normally separated electrodes, one or both of which are to be supported upon a vibratory member individual thereto and each of the electrodes so supported constitutes with its supporting member a moving system having a chosen natural period, and operating when subjected to vibrations of its natural period to enga the electrodes.

The rawing illustrates one embodiment of the invention as applied to a transmitter of the variable resistance type in which the electrodes are normally out of contacting re lationship but wherein the electrodes are designed to engage with each other at the one or more selected frequencies of sound vibration.

This form of transmitter shown comprises a front piate which currics the usual mouthpiece 6. A recess 7 at the rear of the front plate 5 provides a seat for a diaphragm S, which is held in this. reccssliy a clamping ring 9 secured to the front plate A rubber ring 10 surrounding the pnriphery of the diagrams serves to insulate this diaphra m from the front plate and also enables the diaphragm to he held firmly in place between the front plate and the clamping rin 9. r

The variafile resistance element illustrated consists of a pair of electrodes 11 and 12 one being suitably mounted on the diaphragm 8 and the other hein z mounted on' a diaphragm 13. i

The particular transm ter illn=tratcd by the drawing is designed tbe opcrativc only at two substantially different t'rmpicncics of 'in my copcndin;

sound vibration. This is flt(tl{ll[ ll\'llt(l in the present instance 1) mounting the front electrode 11 on one vilirating element. such as the diaphragm 8. and the reaoclrctrode 12 on another vibrating element, such as the diaphragm 13. The actual and relative size and mass of the diaphragms 8 and if! iogether with that of the electrodes ll and l2 and the annular member 14 will depend on the particular frequency or frequcncics to which it is desired to have the transniittcr selectively responsive. The diaphragm t l is mounted on the larger front diaphragm by means of the annular supporting liilinlw-X 14. The diaphragm 8 is of considerably larger diameter than-thp diaphragm l t and hence has a slower period of vibration. in addition, the mass of the diaphragm l t and its supporting member 14 apprcciahlr loiv'crs the frequency ofthc carrying diaphragm 8. Variation of the size, mass. or both, oi any one or more of these elements is relied upon in the production of transmitters responsive to sounds of different particular frequencics. V

This proportioning is such that the natural period of the diaphragm 8 with the clco tro de ll thereon considercd togcthcr is the same as the peri d of one of the sound vibrations to which the transmitter is to he 7" sponsive and is also such that the natural period of the diaphragm 13 with the cleo trode 12 thereon considered together is the same as another of the sound vibrations to which the transmittcnis to be responsive. If it is dcsircd'to have the transmitter responsive to substantially one frcqucniy only. the proportioningy of the diaphragms and their respective electrodes considered togcther will he such that the natural periods thereof will be substantially the same in each case: this pcriod ro he the same as the frequcricy of the particular sound to which it is desired to ha re the transmitter selectively responsive.

The electrodes 11 and IZ 'are preferably of silicon carbide or carhorundum, as disc-i052} atcnt application Scrl Numlicr' 3R9.2l6 led November 19, 1919 and as disclosed in su h pending appgicw tion the electrode It has preferably a 1) one contaoting surface, and the electrodqlg'fl convex' contacting surface having a radius of approxiniatcly eight nietcrs. This feature is not however essential to the present inventiou inasmuch as electrodes of any suitable construction and nniterial can he used in the transmitting device forming the sub ject matter of the present application.

The electrodes 11 and 12 are normally out of Contact, and the constrnctii'm of the transmitter is such that they engage only while the transmitter is subject. to sound vibrations of the frequency or frequencies to which it is selectively responsive. As shown, the eler' trodes ll and "3 cooperate to control the making and breaking of a circuit including in addition thereto a battery 15 and the primary winding of a transformer 16; this circuit being normally open between the elec trodes.

In operation sound vibrations impinging on the diaphragm 8 it in motion and some motion is also imparted thereby to the diaphragm 13; which with its electrode 12 has a certain inertia effect, which, to a liniitcd degree. influences its displacement. The movement of the two diaphrugms 8 and i3 forces the electrodes 11 and 12 toward and away from each other but under proper operating conditions the amplitude of move ment of these claw-trodes is not snllicient to engage them except at. the chosen frequencies, On sound vihrations of the same t're quency as the natural period o1 the dia phragm H and the electrode 11 considered together striking this diaphragm however. an increased amplitude of movement is imparted thereto due to its greater responsivo ness to sounds of its natural period. This increased movement is sulhcient to engage the electrodes 11 and 12 during such vibration and results in alternate completion and interruption of the circuit controlled thereby so long as and as often as sounds of substantially such particular frequency are impressed upon the diaphragm 8. i

The construction of the transmitter is pref erahly such that the movement of the dim phragms 8 and i will not be interfered with by air confin d therehetween; and such interference is prevented in the construction shown by providing a number of IQlil tively large holes 17 in the member 14 to permit free ingress and egress ot air to the space between these electrodes The same general action as described for the diaphragm 8 and electrode 1,) also takes place when sound vibrations of substan tially the same frequency as the natural period of the diaphragm 13 with its electrode 12 considered together reaches the transmitter; the movement of the diaphragrn 13 being increased under these con ditions and thus effecting the engagement of the electrodes 11 and 12 and the alternate interruption of the circuit controlled thereby in the same manner as previously described.

' when the natural periods of the two diaphragms 8 and 13 with their respective electrodes it and 12 are substantially ditlercnt. sound vibrations of frequencies interme diate such natural periods hut substantially ditlerent therefrom. will not uuse the en; gugemcnt ol the electrodes.

During the alternate completion and in terruption of the primary circuit. in re sponse to sound vibrations of the frequency or frequencies to whi h the tin initter is selectively responsive. the current through the iirin'urry winding of the trunslorincr 1G is correspondingly increased and decreased and thus induces similar current lluctua" tions in the secondary winding ol the transformer. l he latter current fluctuations can be readily detected by a suitable receiving or recording device operatively associated with the circuit including the secondary winding of the transformer 16. Inasmuch as no current change talres place in the transformer except in response to the en gagement of the electrodes 11 and 12, the actuation of the receiving or recording de vice by current from the circuit including the secondary winding of the trunstormen serves to indicate that the transmitter is receiving sound vibrations of a frequency to which it is selectively responsive. In event the transmitter seledtively responds to sound vibrations of two substantially different frequencies, as is the case of the transmitter shown, the particular frequency being received by the transmitter may be detected. due to the fact that the sound vi brations having the higher frequency will result in the production of a tone of higher or of a record pitch in the receiving device,

of vibrations indicating a greater number over a given record unit, than are obtained in response to sound vibrations of the lower freiucncy acting on the transmitter.

li hat is claimed is:

l. A sound responsive device of two substantially different. particular frequencies comprising a pair of normally separated electrodes, a vibratory member supporting one of the electrodes, and a. vibratory mem ber supporting the other of the electrodes, each vibratory member and the respective electrode supported then-thy forming a mov ing system having av chosen natural period, and the chosen natural periodof one movingsystem heingsuhstantially different from the chosen natural period of the other mov mg system; one of said vibratory members being supported by the other whereby said electrodes are brought into contact when said moving systems are vibrated at. either of the two chosen natural periods- 2. A sound responsive device comprising a pair of normally separated electrodes, a first diaphragm supporting one of the electrodes, a second diaphragm su ported wholly from the first. diaphragm anilcarrythe same period as the natural ing the other of the electrodes, and means connectin theffirst diaphragm to the second diap ragm, the two diaphragms and the respective electrodes forming a plurality of moving systems each having a chosen natural period; said electrodes being arranged to be brou ht into contact on subjectionof-th'e diap ragms to vibrations of period of one of the moving systems. vi

3. A sound responsive device comprising an electrode, a diaphragm supporting said electrode, an annular member mounted on said diaphragm, a second diaphragm mounted on said annular member, an electrode mounted on said second diaphragm adjacent to but normall separated from said electrode, the two diaphragms and their respectice electrodes forming moving osiysbems, each having a chosen natural 1' said electrodes adapted to be broug t into contact on subjection of the diaphragms to vibrations of the same period as the natural period of me of the moving systems.

4. A sound responsive device of two substantially different particular frequencies comprising an electrode, a diaphragm supporting said electrode, said'diaphragm and electrode comprising a moving system having a chosen natural period, an annular member mounted on said diaphragm, a second diaphra m mounted on said annular member, an e ectrode mounted on said diaphragm adjacent to but normally separated JAMES BUCKNER SPEED. 

